My first go at writing a coding challenge myself. The challenge is to implement
the IOrderPickupNumberSystem interface in the OrderPickupNumberSystem class.
Right now, this class is already implemented with my solution so if you want to
take the challenge yourself you have to delete the contents of that class and
then have Visual Studio add the method stubs. Finally, run the unit tests in
OrderPickupNumberSystem.Tests to verify your work.
Companion blog post: https://cronoxyd.de/order-pickup-number-system